The transportation of extremely heavy items presents many problems with respect to the strength of the container or vessel which carries the heavy object during the transportation. For example, steel cord is used extensively in construction to reinforce concrete or the like. The transportation of such steel cord is difficult considering the extreme weight of a steel cord coil.
Truck trailers specially designed to carry heavy loads are available. However, these truck trailers may be unreasonably expensive, dependent upon the number of times they are actually used to carry heavy loads.
In the past, steel cord coils could only be moved by truck if the truck in question was employing a truck trailer which had no cover. Covered truck trailers could not be used because, as a coil was moved from the rear end of the truck trailer to the front end, above the front wheel axles, the great weight of the steel coil would cause structural damage to the trailer truck bed. In fact, the portion in between the areas above the front and rear wheel axles, of the average trailer truck, cannot support the weight of a steel coil as it is brought over such portion to be loaded. A great disadvantage of employing a truck trailer having no cover is that the steel coils being shipped are continuously exposed to the elements. This exposure causes significant damage to the steel coil.
It is known in the cargo transportation art to use planks or some other type of cantilever bridge span to move cargo from a location where it is being stored into the container or vessel which is to transport the cargo. For example, U.S. Pat. No. 426,209 issued Apr. 22, 1890 to McIntyre teaches a gang plank for transportation of cargo or the like between a loading dock and a vessel. U.S. Pat. No. 1,568,303 issued Jan. 5, 1926 to Webster teaches freight skids which are used in loading and unloading railroad cars and trucking freight to and from floors or platforms at different elevations.
U.S. Pat. No. 571,497 issued Nov. 17, 1896 to Powell teaches a platform which may be inserted within a freight car. The platform carries a gang-plank within a central longitudinal chamber. The purpose and effect of the Powell platform and gangplank is to provide a freight car floor having a gang-plank which can be easily employed in that it is easy to access without disturbing the freight lying on the freight car floor. This device, as other devices of the prior art, teach means for effecting the transportation of cargo from a storage location to a container or vessel over some sort of gap. However, the prior art appears to be silent relative to the problem of transportation of heavy cargo over structurally weak portions within a container or vessel.